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327 lines
13 KiB
<!-------- @HEADER
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! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
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!
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! Zoltan Toolkit for Load-balancing, Partitioning, Ordering and Coloring
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! Copyright 2012 Sandia Corporation
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! Under the terms of Contract DE-AC04-94AL85000 with Sandia Corporation,
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! the U.S. Government retains certain rights in this software.
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! Redistribution and use in source and binary forms, with or without
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! met:
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! 1. Redistributions of source code must retain the above copyright
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! 2. Redistributions in binary form must reproduce the above copyright
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! Questions? Contact Karen Devine kddevin@sandia.gov
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! Erik Boman egboman@sandia.gov
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! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
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! @HEADER
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------->
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<!doctype html public "-//w3c//dtd html 4.0 transitional//en">
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<html>
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<head>
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<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
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<meta name="GENERATOR" content="Mozilla/4.76 [en] (X11; U; Linux 2.4.2-2smp i686) [Netscape]">
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<meta name="sandia.approval_type" content="formal">
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<meta name="sandia.approved" content="SAND2007-4748W">
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<meta name="author" content="Zoltan PI">
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<title>Zoltan User's Guide: Load-Balancing Algorithms and Parameters</title>
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</head>
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<body bgcolor="#FFFFFF">
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<div align=right><b><i><a href="ug.html">Zoltan User's Guide</a>
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| <a href="ug_alg_simple.html">Next</a> | <a href="ug_param.html">Previous</a></i></b></div>
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<!---------------------------------------------------------------------------->
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<h2>
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<a NAME="Algorithms"></a>Load-Balancing Algorithms and Parameters</h2>
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The following dynamic load-balancing algorithms are currently included
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in the Zoltan library:
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<blockquote>
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<br><a href="ug_alg_simple.html">Simple Partitioners for Testing</a>
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<blockquote>
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<a href="ug_alg_block.html">Block Partitioning (BLOCK)</a>
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<br><a href="ug_alg_cyclic.html">Cyclic Partitioning (CYCLIC)</a>
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<br><a href="ug_alg_random.html">Random Partitioning (RANDOM)</a>
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</blockquote>
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<a href="ug_alg_geom.html">Geometric (Coordinate-based) Partitioners</a>
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<blockquote>
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<a href="ug_alg_rcb.html">Recursive Coordinate Bisection (RCB)</a>
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<br><a href="ug_alg_rib.html">Recursive Inertial Bisection (RIB)</a>
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<br><a href="ug_alg_hsfc.html">Hilbert Space-Filling Curve Partitioning (HSFC)</a>
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<br><a href="ug_alg_reftree.html">Refinement Tree Based Partitioning (REFTREE)</a>
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<!----------
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<br><a href="ug_alg_oct.html">Octree/Space-Filling Curve (SFC) Partitioning (OCT)</a>
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----------->
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</blockquote>
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<a href="ug_alg_hypergraph.html">Hypergraph Partitioning, Repartitioning and Refinement (HYPERGRAPH)</a>
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<blockquote>
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<a href="ug_alg_phg.html">PHG</a>
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<br><a href="ug_alg_patoh.html">PaToH</a>
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</blockquote>
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<a href="ug_alg_graph.html">Graph Partitioning and Repartitioning (GRAPH)</a>
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<blockquote>
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<a href="ug_alg_phg.html">PHG</a>
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<br><a href="ug_alg_parmetis.html">ParMETIS</a>
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<br><a href="ug_alg_ptscotch.html">Scotch</a>
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</blockquote>
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<a href="ug_alg_hier.html">Hybrid Hierarchical Partitioning (HIER)</a>
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</blockquote>
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The parenthetical string is the parameter value for <i><a href="#LB_METHOD">LB_METHOD</a></i>
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parameter; the parameter is set through a call to <b><a href="ug_interface_init.html#Zoltan_Set_Param">Zoltan_Set_Param</a></b>.
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<p>For further analysis and discussion of some of the algorithms, see [<a href="ug_refs.html#hendrickson-devine">Hendrickson
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and Devine</a>].
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<p><!---------------------------------------------------------------------------->
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<h3>
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<a NAME="LB Parameters"></a>
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<hr><b>Load-Balancing Parameters</b></h3>
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While the overall behavior of Zoltan is controlled by <a href="ug_param.html">general
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Zoltan parameters</a>, the behavior of each load-balancing method is controlled
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by parameters specific to partitioning which are also set by calls to <b><a href="ug_interface_init.html#Zoltan_Set_Param">Zoltan_Set_Param</a></b>.
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Many of these parameters are specific to individual partitioning algorithms,
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and are listed in the descriptions of the individual algorithms.
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However, several have meaning across multiple partitioning algorithms.
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These load-balancing parameters are described below. Unless indicated otherwise,
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these parameters apply to both <b><a href="ug_interface_lb.html#Zoltan_LB_Partition">Zoltan_LB_Partition</a></b>
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and
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<b><a href="ug_interface_lb.html#Zoltan_LB_Balance">Zoltan_LB_Balance</a></b>.
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<br>
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<table WIDTH="100%" NOSAVE >
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<tr VALIGN=TOP>
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<td VALIGN=TOP><b>Parameters:</b></td>
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<td></td>
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</tr>
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<tr VALIGN=TOP NOSAVE>
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<td NOSAVE><a NAME="LB_METHOD"></a> <i>LB_METHOD</i></td>
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<td>The load-balancing algorithm used by Zoltan is specified by this parameter.
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Valid values are
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<blockquote>
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BLOCK (for <a href="ug_alg_block.html">block partitioning</a>),
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<br>RANDOM (for <a href="ug_alg_random.html">random partitioning</a>),
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<br>RCB (for <a href="ug_alg_rcb.html">recursive coordinate bisection</a>),
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<br>RIB (for <a href="ug_alg_rib.html">recursive inertial bisection</a>),
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<br>HSFC (for <a href="ug_alg_hsfc.html">Hilbert space-filling curve
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partitioning</a>),
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<br>REFTREE (for <a href="ug_alg_reftree.html">refinement tree based
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partitioning</a>)
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<br>GRAPH (to choose from collection of methods for <a href=ug_alg_graph.html>graphs</a>),
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<br>HYPERGRAPH (to choose from a collection of methods for <a href=ug_alg_hypergraph.html>hypergraphs</a>),
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<!--------------
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<br>OCTPART (for <a href="ug_alg_oct.html">octree partitioning</a>),
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---------------->
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<br>HIER (for hybrid <a href="ug_alg_hier.html">hierarchical partitioning</a>)
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<br>NONE (for no load balancing).</blockquote>
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</td>
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</tr>
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<tr>
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<td style="vertical-align: top;"><span style="font-style: italic;"> <a name="LB_APPROACH"></a>LB_APPROACH</span><br>
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</td>
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<td style="vertical-align: top;">The desired load balancing
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approach.
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Only <i>LB_METHOD</i> = <a href="ug_alg_hypergraph.html">HYPERGRAPH</a> or
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<a href="ug_alg_graph.html">GRAPH</a>
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uses the <i>LB_APPROACH</i> parameter. Valid values are
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<blockquote>
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PARTITION (Partition "from scratch," not taking
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into account the current data distribution; this option is recommended
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for static load balancing.)<br>
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REPARTITION (Partition but take into account current data
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distribution to keep data migration low; this option is recommended for
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dynamic load balancing.)<br>
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REFINE (Quickly improve the current data
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distribution.)<br>
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</blockquote>
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</td>
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</tr>
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<tr VALIGN=TOP NOSAVE>
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<td NOSAVE><a NAME="NUM_GLOBAL_PARTS"></a> <i>NUM_GLOBAL_PARTS</i></td>
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<td>The total number of parts to be generated by a call to <b><a href="ug_interface_lb.html#Zoltan_LB_Partition">Zoltan_LB_Partition</a></b>.
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Integer values greater than zero are accepted. Not valid for
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<b><a href="ug_interface_lb.html#Zoltan_LB_Balance">Zoltan_LB_Balance</a></b>. </td>
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</tr>
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<tr VALIGN=TOP NOSAVE>
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<td NOSAVE><a NAME="NUM_LOCAL_PARTS"></a> <i>NUM_LOCAL_PARTS</i></td>
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<td>The number of parts to be generated on this processor by a call
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to <b><a href="ug_interface_lb.html#Zoltan_LB_Partition">Zoltan_LB_Partition</a></b>.
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Integer values greater than or equal to zero are accepted. Not valid for <b><a href="ug_interface_lb.html#Zoltan_LB_Balance">Zoltan_LB_Balance</a></b>.
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If any processor sets this parameter, NUM_LOCAL_PARTS is assumed to be
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zero on processors not setting this parameter.
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</td>
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</tr>
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<tr VALIGN=TOP NOSAVE>
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<td NOSAVE><a NAME="RETURN_LISTS"></a> <i>RETURN_LISTS</i></td>
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<td>The lists returned by calls to
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<b><a href="ug_interface_lb.html#Zoltan_LB_Partition">Zoltan_LB_Partition</a></b>
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or
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<b><a href="ug_interface_lb.html#Zoltan_LB_Balance">Zoltan_LB_Balance</a></b>. Valid values are
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<blockquote>
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<br>"IMPORT", to return only information about objects to
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be imported to a processor
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<br>"EXPORT", to return only information about
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objects to be exported from a processor
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<br>"ALL", or "IMPORT AND EXPORT" (or any string with both "IMPORT"
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and "EXPORT" in it) to return both import and export information
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<br> "PARTS" (or "PART ASSIGNMENT" or any string with "PART" in it)
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to return the new process and part
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assignment of every local object, including those not being
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exported.
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<br>"NONE", to return neither import nor export information
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</blockquote>
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</td>
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</tr>
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<tr VALIGN=TOP NOSAVE>
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<td NOSAVE><a NAME="REMAP"></a> <i>REMAP</i></td>
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<td>Within
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<b><a href="ug_interface_lb.html#Zoltan_LB_Partition">Zoltan_LB_Partition</a></b>
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or
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<b><a href="ug_interface_lb.html#Zoltan_LB_Balance">Zoltan_LB_Balance</a></b>,
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renumber parts to maximize overlap between the old decomposition and
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the new decomposition (to reduce data movement from old to new decompositions).
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Valid values are "0" (no remapping) or "1" (remapping). Part assignments from
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<a href="ug_query_lb.html#ZOLTAN_PART_MULTI_FN">ZOLTAN_PART_MULTI_FN</a> or
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<a href="ug_query_lb.html#ZOLTAN_PART_FN">ZOLTAN_PART_FN</a> query functions
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can be used in remapping if provided; otherwise, processor numbers are used
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as part numbers. Requests for remapping
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are ignored when, in the new decomposition, a part is spread across
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multiple processors or part sizes are specified using <a href="ug_interface_lb.html#Zoltan_LB_Set_Part_Sizes"><b>Zoltan_LB_Set_Part_Sizes</b>.</a></td>
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</tr>
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<tr VALIGN=TOP NOSAVE>
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<td NOSAVE><a NAME="IMBALANCE_TOL"></a> <i>IMBALANCE_TOL</i></td>
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<td>The amount of load imbalance the partitioning algorithm should deem
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acceptable. The load on each processor is computed as the sum of the weights
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of objects it is assigned. The imbalance is then computed as the maximum
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load divided by the average load. An value for <i>IMBALANCE_TOL</i> of
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1.2 indicates that 20% imbalance is OK; that is, the maximum over the average
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shouldn't exceed 1.2. </td>
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</tr>
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<tr VALIGN=TOP NOSAVE>
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<td NOSAVE><a NAME="MIGRATE_ONLY_PROC_CHANGES"></a> <i>MIGRATE_ONLY_PROC_CHANGES</i></td>
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<td>If this value is set to TRUE (non-zero), Zoltan's migration functions will
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migrate only objects moving to new processors. They will not migrate objects
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for which only the part number has changed; the objects' processor numbers
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must change as well. If this value is set to FALSE (zero), Zoltan's migration
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functions will migrate all objects with new part or processor assignments.
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</td>
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</tr>
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<tr VALIGN=TOP NOSAVE>
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<td NOSAVE><a NAME="AUTO_MIGRATE"></a> <i>AUTO_MIGRATE</i></td>
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<td>If this value is set to TRUE (non-zero), Zoltan will automatically
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perform the data migration during calls to <b><a href="ug_interface_lb.html#Zoltan_LB_Partition">Zoltan_LB_Partition</a></b>
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or
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<b><a href="ug_interface_lb.html#Zoltan_LB_Balance">Zoltan_LB_Balance</a></b>.
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A full discussion of automatic migration can be found in the description
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of the <a href="ug_interface_mig.html">migration interface functions</a>. </td>
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</tr>
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<tr VALIGN=TOP>
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<td VALIGN=TOP><a NAME="Default_Parameter_Values"></a><b>Default Values:</b></td>
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<td></td>
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</tr>
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<tr VALIGN=TOP>
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<td></td>
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<td><i>LB_METHOD</i> = RCB</td>
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</tr>
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<tr VALIGN=TOP>
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<td></td>
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<td><i>LB_APPROACH</i> = REPARTITION</td>
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</tr>
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<tr VALIGN=TOP>
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<td></td>
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<td><i>NUM_GLOBAL_PARTS</i> = Number of processors specified in
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<b><a href="ug_interface_init.html#Zoltan_Create">Zoltan_Create</a></b>.</td>
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</tr>
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<tr VALIGN=TOP>
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<td></td>
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<td><i>NUM_LOCAL_PARTS</i> = 1</td>
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</tr>
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<tr VALIGN=TOP>
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<td></td>
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<td><i>RETURN_LISTS</i> = ALL</td>
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</tr>
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<tr VALIGN=TOP>
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<td></td>
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<td><i>REMAP</i> = 1</td>
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</tr>
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<tr VALIGN=TOP>
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<td></td>
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<td><i>IMBALANCE_TOL</i> = 1.1</td>
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</tr>
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<tr VALIGN=TOP>
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<td></td>
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<td><i>MIGRATE_ONLY_PROC_CHANGES</i> = 1</td>
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</tr>
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<tr VALIGN=TOP>
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<td></td>
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<td><i>AUTO_MIGRATE</i> = FALSE</td>
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</tr>
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</table>
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<p><!---------------------------------------------------------------------------->
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<hr WIDTH="100%">[<a href="ug.html">Table of Contents</a> | <a href="ug_alg_simple.html">Next:
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Simple Partitioners for Testing</a> | <a href="ug_param.html">Previous:
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Zoltan Parameters and Output Levels</a> | <a href="https://www.sandia.gov/general/privacy-security/index.html">Privacy and Security</a>]
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